x-y=4 4x+2y=-1
来源:百度知道 编辑:UC知道 时间:2024/05/16 00:56:45
用代入法
x=y+4
代入4x+2y=-1
4(y+4)+2y=-1
4y+16+2y=-1
6y=-17
y=-17/6
x=y+4=7/6
X=y+4
代入
4x+2y=-1
得
4(y+4)+2y=-1
解得 y=-17/6
x=7/6
x=y+4
代入
4(y+4)+2y=-1
6y=-17
y=-17/6
x=7/6
解:由一式得
x=4+y
代入二式
4(4+y)+2y=-1
解得
y=-17/6
x=7/6
x-y=4 4x+2y=-1....................(1)
4x+2y=-1....................(2)
(1)×2得2x-2y=8....................(3)
(3)+(2)得6x=7
x=6/7
y=-17/6
∴原方程组的解为
x=6/7,y=17/6
x=4+y
4(4+y)+2y=-1
6y=-17
y=-17/6
x=7/6
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